Troubleshooting websites that share one root...

We have a client who's website consists of 2 URLs - 1 for the USA, and ! that is divided into English and French for Canada but both website configurations use the same root.

Ever since we migrated to IIS 7.5, the Canadian English or French site will intermittently go down (HTTP requests time out) and then the Main USA one will do the same.

I have created one app pool for each segment, tuned everything I know how, and still we have problems with the server's uptime. I know there must be a conflict somewhere, but I haven't found it yet and wanted to ask for help. I can post the web.config files if that helps, but I'm trying to get an idea of where I should be looking to try and resolve this issue.